1. Field of the Invention
The present invention relates to a light scanning device used in an image reader and an image recording apparatus.
2. Description of the Prior Arts
A photo-printer, a laser printer, and the like are provided with a light scanning device for converging a light beam emitted from a light source on a scanned surface as a light spot and scanning the light spot on the scanned surface. The light scanning device is provided with a polygon mirror for scanning the light beam, and scanning lenses for focusing the light beam. However, there is a problem that a printing trouble so-called “ghost” occurs on the scanned surface due to multiple reflections of a part of the light beam between the optical members.
Japanese Patent Laid-Open Publications No. 9-33842 and No. 5-346553 propose to remove reflection components by rotating the scanning lens in the main scanning direction, so that the ghost caused by the multiple reflections is prevented.
In addition, Japanese Patent Laid-Open Publication No. 9-274134 proposes to prevent the ghost caused by the reflection on the flat covering plate by tilting the flat covering plate, which constitutes a part of the housing for sealing the polygon mirror.
However, in Japanese Patent Laid-Open Publications No. 9-33842 and No. 5-346553, there is another problem that the scanning line is curved in a sub-scanning direction by tilting the scanning lens. This curvature of the scanning line, so-called “bowing” deteriorates the image quality. Although Japanese Patent Laid-Open Publication No. 9-274134 is provided with an extra flat plate for correcting the curvature of the scanning line caused by tilting the flat covering plate, the scanning device becomes complicated and the manufacturing cost is raised.